Impurity effects on a 2-leg spin ladder compound SrCu2O3

Abstract Measurements of magnetic susceptibility, specific heat and inelastic neutron scattering were performed on a Zn-substituted spin- 1 2 Heisenberg 2-leg ladder compound Sr(Cu 1− x Zn x ) 2 O 3 ( x ≤ 0.08) to investigate nonmagnetic impurity effects on the quantum spin system with a large spin gap of about ∼ 400 K. A clear anomaly attributed to the onset of antiferromagnetic ordering was observed both in the magnetic susceptibility and specific heat data even at only 1 % of Zn. The Neel temperature showed a systematic Zn-concentration dependence with a broad maximum at around 4 % substitution ( T Nmax ∼ 8K). A finite amount of T-linear term with a coefficient of γ ∼ 3.5 mJ/K 2 was observed in the specific heat above T N for x = 0.02 and 0.04, suggesting the existence of a finite density of state at E = 0 in the spin excitation spectrum as supported by the inelastic neutron scattering measurement.